Different applications using a single data storage system may have different performance and/or availability requirements for the associated storage. Each application, typically run on a host, may have different capacity, performance, and/or availability requirements for storage allocated to it on the data storage system. A data storage system, which may include one or more arrays of data storage devices, generally does not receive performance and/or availability requirements for individual host applications using its storage devices.
Data storage systems may run programs, or tools, to “optimize” storage within the array. One such optimization tool is the SYMMETRIX OPTIMIZER tool, available from EMC Corporation of Hopkinton, Mass. This tool measures the usage of specific components of a SYMMETRIX storage system, also available from EMC Corp. The tool seeks to identify highly utilized components of the storage system so that the load on components within the storage system can be balanced. For example, the tool may measure the number of I/O requests handled by each physical device, or spindle, within the data storage system per unit of time. The tool uses such measurements to make decisions regarding how storage should be allocated or configured. The program may migrate data to other physical devices on the storage system in an effort to optimize overall system performance. For example, when one component is highly utilized, the tool may move selected data from that component to another component that is less utilized. To maintain the integrity of the storage for the application, the storage characteristics of the target component—including capacity, performance, availability, and RAID level—must match or exceed the storage characteristics of the source component.
The AutoRAID tool, available from Hewlett Packard, is another tool that can be used to optimize storage within a data storage system. The AutoRAID tool can change the RAID level of devices in the data storage system to improve the performance of the data storage system.
Data storage systems may also run tools that monitor the quality of service of the data storage system and make adjustments to maintain the specified level of service. These tools attempt to maintain the quality of service by managing the priority of operations in the data storage system and I/O requests from hosts using the system.